概述
连铸钢包下渣检测装置用于炼钢连铸过程中检测钢包水口的下渣含量，以提高中间包钢水洁净度，获得钢包钢水最佳收得率，该装置采用电磁感应检测原理。
下渣检测的意义
实现高产量：为保证钢包内钢水的洁净度，如果用肉眼检测炉渣，往往会过早关包，这样会降低钢水的收得率。但如果使用炉渣检测系统，可以准确及时地检测炉渣，使钢水残渣量控制在1%-2%，实现高产量。
提高钢水洁净度：炼钢渣进入中间包是影响成品钢水洁净度的主要原因，使用钢渣检测系统可以使带入中间包的炼钢渣量降到极小，同时可以减少铸坯表面缺陷至少80%。
避免喷嘴堵塞：炼钢渣进入中间包也是二次氧化造成喷嘴堵塞的主要原因，使用渣检测系统后，可以大大减少喷嘴堵塞的情况。
系统组成
下渣检测系统主要由传感器、前置放大器、信号处理单元、中央处理器和平台控制箱五部分组成。
系统控制流程图
传感器的工作原理
The sensor adopts the principle of electromagnetic induction for signal detection, and its typical structure is two concentric coils. When the primary coil is supplied with an intermediate frequency excitation current, due to the action of the magnetic field, an eddy current is generated in the steel flow, and the direction of the magnetic field is opposite to the direction of the magnetic field generated by the coil. Because the conductivity of slag is much lower than that of molten steel at high temperature (about 1/1000), the eddy currents generated in slag are much smaller than those generated in molten steel. In the process of pouring steel, all the molten steel flows out at the beginning of pouring. At the later stage of pouring, there will be steelmaking slag mixing out, which reduces the conductivity of the melt and enhances the electromagnetic field. This signal is measured by the secondary coil.
The principle of sensor construction
The primary coil and the secondary coil are isolated by high temperature resistant materials, and the coils are encapsulated in a flat ring made of special steel as a whole. Then two pairs of signal lines are drawn from the two-pole coil using a unique technical method, and sent to the secondary part.
The installation of the sensor
The sensor is installed in the ladle reference plate, coaxial with the ladle nozzle, and acts as a guide part for the ladle nozzle casing tube at the same time.
The technical features
The coil made of imported materials and installed at the bottom of the ladle as a guide component for the ladle nozzle can work normally in an environment of 900 °C for a long time, achieving no burning, no damage and good weak slag signal detection characteristics . The average service life of the sensor reaches more than 800 furnaces.
The signal connector of the ladle slag coil can meet the reliable connection of the microvolt level (1μV=10-6V) slag signal under the conditions of high temperature, high impedance and strong oxidation, and realize the repeated use of long-term zero impedance.
After the ladle slag coil works for a long time in a high temperature environment, changes in distributed parameter characteristics such as impedance cause signal drift. The system can automatically identify and compensate, which ensures the accuracy of system signal processing and alarming.
The function is complete, which can actually reflect various information of molten steel casting. It has various functions such as curve storage, status display, alarm display, output control, and information printing, etc., which can effectively meet the requirements of the production process.
The technical indexes
Sampling time: <10ms
System response time: <0.1s
Zero point average volatility: <4%
System detection value accuracy: <5% (duty ratio)
Slag volume alarm setting value: user-defined (recommended to use 20%)
Average sensor life: >800 heats
The working condition
Sensor use ambient temperature: <900℃
二次仪表工作温度：<40℃
二次仪表储运温度：-20℃-+70℃
